This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A338248 #14 Oct 18 2020 22:33:17 %S A338248 0,1,4,5,2,3,16,17,14,15,20,21,18,19,8,9,6,7,12,13,10,11,64,65,62,63, %T A338248 68,69,66,67,56,57,54,55,60,61,58,59,80,81,78,79,84,85,82,83,72,73,70, %U A338248 71,76,77,74,75,32,33,30,31,36,37,34,35,24,25,22,23,28,29 %N A338248 Nonnegative values in A053985, in order of appearance. %C A338248 This sequence is a self-inverse permutation of the nonnegative integers (the offset has been set to 0 so as to get a permutation). %C A338248 There are only two fixed points: a(0) = 0 and a(1) = 1. %H A338248 Rémy Sigrist, <a href="/A338248/b338248.txt">Table of n, a(n) for n = 0..5461</a> %H A338248 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a> %F A338248 a(0) = 0. %F A338248 a(n) = A053985(A053738(n)) for any n > 0. %e A338248 A053985 = 0, 1, -2, -1, 4, 5, 2, 3, -8, -7, -10, -9, -4, -3, -6, -5, 16, 17, ... %e A338248 We keep: 0, 1, 4, 5, 2, 3, 16, 17, ... %o A338248 (PARI) A053985(n) = fromdigits(binary(n), -2) %o A338248 print (select(v -> v>=0, apply(A053985, [0..109]))) %Y A338248 See A338245 for a similar sequence. %Y A338248 Cf. A053738, A053985, A338249. %K A338248 nonn,base %O A338248 0,3 %A A338248 _Rémy Sigrist_, Oct 18 2020